Browsing by Author "Romero, Julio"

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    ELECTROCHEMICAL METHOD FOR SULFITE DETERMINATION IN WINES BY ELECTROCHEMICAL RESPONSE USING A MEMBRANE ABSORBER SYSTEM
    (SOC CHILENA QUIMICA, 2016) Arce, Roxana; Baez, Carla; Muena, J. P.; Aguirre, Maria J.; Romero, Julio
    This research demonstrates how the sulfite content can be measured by cyclic voltammetry using a previously reported membrane absorber system, which separates efficiently sulfite present in wine. Results obtained show notably similar values to those obtained for the same wine samples using modified MonierWilliams method (aspiration method) and Ripper method. The membrane absorber system allows the release of the free SO2, and can be used to determine the sulfur dioxide present in juices and other foods that contain high concentrations of phenols, polyphenols and other structurally related compounds that act as interferers in the electrochemical oxidation of sulfite. The absorber solution allows a direct measurement without change in pH or added electrolyte, facilitating the determination of great amounts of samples from diverse wines using only one calibration curve. In this way, a system that allows the detection of sulfite and that can be used in vineyards is obtained.
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    Extraction of sulfite for wastewater treatment and for analytical determination
    (2019) Canales , J. P.; Arce, Roxana; Madariaga, C.; García, Macarena del Pilar; Canales Oyarzo, Camila Pía; Vélez, Jorge H.; Arévalo, María del Carmen; Aguirre, María J.; Romero, Julio
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    Hydrophobic eutectic solvents for the selective solvent extraction of molybdenum (VI) and rhenium (VII) from a synthetic pregnant leach solution
    (2023) Olea, Felipe; Valenzuela, Matias; Zurob, Elsie; Parraguez, Benjamin; Abejon, Ricardo; Cabezas, Rene; Merlet, Gaston; Tapia, Ricardo; Romero, Julio; Quijada-Maldonado, Esteban
    In this work, a study on the selective solvent extraction (SX) of molybdenum (Mo) and rhenium (Re) from a synthetic pregnant leach solution (PLS) has been carried out using nine different hydrophobic eutectic solvents (HES). Experiments were carried out using pure HES to evaluate the selective extraction and the subsequent stripping of these metal ions; then, the best HES was dissolved in kerosene to study the SX stoichiometry. Results indicated that only TOPO-based and N8881-Cl-based HES did not form emulsions, third phases or precipitates. These HES achieved a selective extraction because these obtained almost a 100% extraction towards Mo and Re from the PLS and very low extractions for Copper (Cu) and Iron (Fe) in one equilibrium stage. The stripping experiments showed that 95% of Mo and 22% of Re were stripped out from the loaded TOPO-based HDES, respectively, opening the possibility for the selective stripping of the metal species for further purification. Finally, the extraction stoichiometry was proposed based on an experimental slope analysis and the measurement of cations and anions transferred into the aqueous phase in which HES acts as a neutral extractant in the complexation of the Mo and Re salts. These promising results suggest that HES could be attractive for more sustainable mining industry.
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    Rhenium(VII) extraction from sulfuric aqueous solutions using ionic liquids as diluent and extractant: insights on the extraction stoichiometry and process parameters
    (2022) Quijada-Maldonado, Esteban; Roman, Rodrigo; Merlet, Gaston; Perez, Barbara; Cabezas, Rene; Tapia, Ricardo; Olea, Felipe; Villarroel, Eduardo; Araya-Lopez, Claudio; Romero, Julio
    BACKGROUND Rhenium(Re) is a highly valuable metal recovered from molybdenite leach liquors by solvent extraction (SX) using toxic organic solvents. This work proposes an extracting phase free of volatile organics composed by the ionic liquid (IL) trioctylmethylammonium benzoate [TOMA][BA] as the extractant, due to its ability to extract Re(VII), and the IL 1-octyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide [omim][Tf2N] as the diluent, due to its high hydrophobicity where the extraction stoichiometry and process parameters such as the initial pH, the extractant concentration in the diluent and stripping using ammonium hydroxide (NH4OH) and sodium hydroxide (NaOH) were assessed. RESULTS This extracting phase yielded high extraction percentages: 95% with only 3% (v/v) of [TOMA][BA] in [omim][Tf2N]. A detailed study of the SX stoichiometry was carried out through slope analysis, showing that the SX occurs in two steps: first, the extraction of acid; then, the extraction of the metal ion via anion exchange with the transfer of IL-diluent anion to the aqueous phase. Additionally, the extracting phase was tested in a synthetic molybdenite leached pregnant leach solution, showing selectivity towards Re(VII) over Cu(II) and Fe(III) at very low extractant concentration. The stripping of Re(VII) from the loaded phase was also studied achieving 60% stripping in only one equilibrium step when using NH4OH. CONCLUSION This novel extracting phase, free of volatile organic, shows promising Re(VII) extraction for future industrial applications. (c) 2021 Society of Chemical Industry (SCI).
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    Task-Specific Ionic Liquids as Extractants for the Solvent Extraction of Molybdenum(VI) from Aqueous Solution Using Different Commercial Ionic Liquids as Diluents
    (2018) Quijada Maldonado, Esteban; Sánchez, Felipe; Pérez, Bárbara; Tapia Apati, Ricardo; Romero, Julio